Spinal fixation including lumbar sacral fusion and correcting spinal deformities such as scoliotic curves are well known and frequently used medical procedures. Spinal fixation systems, used to correct problems in the lumbar and thoracic portions of the spine, are frequently installed posterior to the spine on opposite sides of the spinous process and adjacent to the laminae or transverse process. Such systems often include spinal instrumentation having connective structures such as rods or plates extending between and attached with selected vertebrae using bone screws, lamina clamp assemblies and/or vertebra hook assemblies.
Pedicle, lateral and oblique mounting means may be used to secure the spinal instrumentation to the portion of the spine which has been selected to be fused by arthrodesis. Screws, hooks, claws and clamps have been designed to attach spinal instrumentation to selected vertebrae of the spine. Cross linking of spinal instrumentation is designed to prevent migration of the connective structures and to increase stiffness of the associated surgical construct. Even with rigid cross-linking spinal instrumentation is designed to provide only temporary fixation until solid bone fusion has been completed.
Various types of screws, clamps, hooks and claws have been used to attach spinal instrumentation to selected portions of a patient's spine. Examples of pedicle clamps and lamina hooks are shown in U.S. Pat. Nos. 5,005,562; 5,007,909; 5,074,864; 5,102,412; and 5,147,359. Examples of pedicle screws and other types of connectors are shown in U.S. Pat. Nos. 4,763,644; 4,805,602; 4,887,596; 4,950,269; and 5,129,388. These patents are incorporated by reference for all purposes within this application.
Frequently, spinal instrumentation having dual rods or dual plates is difficult to properly install and to cross link on opposite sides of a patient's spine. Both rods and plates must be contoured and adjusted for the desired spinal correction. Unbalanced loading may result in surgical constructs having dual rods or plates. Many types of existing spinal instrumentation require a relative large incision and extensive manipulation of the spinal instrumentation to form the desired surgical construct.
A need has thus arisen for improved connectors to attach spinal instrumentation to selected portions of a patient's spine.